Encyclopedia of Microtonal Music Theory

bike chain, bicycle chain

A metaphor coined by Joseph Pehrson to explain one aspect of 72edo, which describes multiple instances of the closed 12edo pitch-set
transposed by microtonal (in the sense of "less than a semitone") intervals, as similar to the derailleur
mechanism on modern bicycles. The concept can apply to any EDO with a cardinality which is an even multiple of a lower-cardinality EDO.
As an example, below is a diagram showing how this works for 72edo, as 6 bicycle-chains of 12edo. Firstly, take a look at the legend for the HEWM 72edo music notation accidentals.

HEWM-base 72edo Music Notation

In the "NOTATION" section of the table below, notes which are presented horizontally adjacent are enharmonically equivalent. Notes which line up vertically are on the same bike-chain.
8 different symbols in addition to the letter-names: